(a) Partial or final closure of new and existing classified waste management units shall be in compliance with the provisions of this article. If a unit has been partially closed in accordance with an approved closure plan by the effective date of these regulations, the cover over the closed portion does not need to be modified to conform to these regulations, unless monitoring data indicate impairment of beneficial uses of ground water. Classified waste management units shall be closed according to an approved closure and post-closure maintenance plan which provides for continued compliance with the applicable standards for waste containment and precipitation and drainage controls in Article 4 of this chapter, and the monitoring program requirements in Article 5 of this chapter, throughout the closure and post-closure maintenance period. The post-closure maintenance period shall extend as long as the wastes pose a threat to water quality. For land treatment facilities, the postclosure maintenance period shall extend until treatment is complete.

(b) Closure shall be under the direct supervision of a registered civil engineer or a certified engineering geologist.

(c) [Reserved.]

(d) Closed waste management units shall be provided with at least two permanent monuments installed by a licensed land surveyor or a registered civil engineer, from which the location and elevation of wastes, containment structures, and monitoring facilities can be determined throughout the post-closure maintenance period.

(e) Vegetation for closed waste management units shall be selected to require minimum irrigation and maintenance, and shall not impair the integrity of containment structures including the final cover.

(f) The regional board shall require the discharger to establish an irrevocable closure fund or provide other means to ensure closure and post-closure maintenance of each classified waste management unit in accordance with an approved plan.